1. "Digital Media Primer" Yue-Ling Wong, Copyright (c)2013 by Pearson Education, Inc. All rights reserved.

2. Chapter 6 Fundamentals of Digital Video
Part 2
Basic Terminiology

3. In this lecture, you will learn:
These basic terminology in digital video:
frame size
frame aspect ratio
pixel aspect ratio
timecode

4. Sampling and Quantization of Motion
Temporal:
sampling rate:
how frequent you take a snapshot of the motion
frame rate
higher sampling rate: higher frame rate
higher frame rate  more frames for the same duration  larger file size

5. Sampling and Quantization of Motion
Each snapshot: a frame
an image
digitized based on the same concepts of sampling and quantization of images

6. Frame Size Resolution of the frame image Measured in pixel dimensions
No ppi setting: Unlike digital images, there is no pixel per inch (ppi) setting for video because video is not intended for print but for on screen display.

7. Frame Size Examples Frame size NTSC standard definition
720 x 480 pixels
high definition HDV format
1280 x 720 pixels
1440 x 1080 pixels
PAL
720 x 576 pixels

8. Frame Aspect Ratio the ratio of a frame's viewing width to height
NOT equivalent to ratio of the frame’s pixel width to height.

9. Frame Aspect Ratio Examples
4:3
16:9
Example:
Standard definition NTSC standard format
Examples:
Standard definition NTSC wide-screen format
High definition digital video
High definition TV

10. Ratio Does Not Match Up?
Frame size of a NTSC standard definition DV frame: 720 x 480
720 : 480 = 3 : 2
NOT 4 : 3 or 16 : 9
This is because the pixels are not square!

11. Pixel Shapes Digital images: square pixels
Digital video: may not be square pixels

12. Pixel Aspect Ratio Ratio of pixel width : pixel height
Pixel Shape 1
square
< 1
tall
> 1
wide

13. Pixel Aspect Ration Examples
Video Format
Pixel Aspect Ratio
Standard format of standard definition
(e.g. standard format of the non-blu-ray movies DVD)
0.9
Wide-screen format of standard definition
(e.g. wide-screen format of the non-blu-ray movies DVD)
1.2
HDV 720p,
QuickTime movies
1.0
HDV 1080i and 1080p
1.333

14. Let's see if the ratios match up

15. Standard Format Standard Definition
Pixel aspect ratio = 0.9
Frame size = 720  480
Frame aspect ratio = 720  0.9 : 480 = 648 : 480  4 : 3

16. Wide-screen Format Standard Definition
Pixel aspect ratio = 1.2
Frame size = 720  480
Frame aspect ratio = 720  1.2 : 480 = 864: 480  16 : 9

17. HDV 720p Pixel aspect ratio = 1.0 Frame size = 1280  720
Frame aspect ratio = 1280  1.0 : 720 = 1280 : 720 = 16 : 9

18. HDV 1080i and 1080p Pixel aspect ratio = 1.333
Frame size = 1440  1080
Frame aspect ratio = 1440  : 1080  1920 : 1080 = 16 : 9

19. Video image will be distorted if it is displayed on a system with a different pixel aspect ratio.

20. For a video of pixel aspect ratio of 1
Displayed correctly on a system of pixel aspect ratio of 1
Displayed incorrectly on a system of pixel aspect ratio of 0.9.
The image looks stretched vertically.

21. For a video of pixel aspect ratio of 1
Displayed correctly on a system of pixel aspect ratio of 1
Displayed incorrectly on a system of pixel aspect ratio of 1.2.
The image looks stretched horizontally.

22. For a video of pixel aspect ratio of 0.9
Displayed correctly on a system of pixel aspect ratio of 0.9
Displayed incorrectly on a system of pixel aspect ratio of 1.
The image looks slightly stretched horizontally.

23. For a video of pixel aspect ratio of 0.9
Displayed correctly on a system of pixel aspect ratio of 0.9
Displayed incorrectly on a system of pixel aspect ratio of 1.2.
The image looks stretched horizontally.

24. For a video of pixel aspect ratio of 1.2
Displayed correctly on a system of pixel aspect ratio of 1.2
Displayed incorrectly on a system of pixel aspect ratio of 0.9.
The image looks stretched vertically.

25. For a video of pixel aspect ratio of 1.2
Displayed correctly on a system of pixel aspect ratio of 1.2
Displayed incorrectly on a system of pixel aspect ratio of 1.0.
The image looks slightly stretched vertically.

26. Pixel Aspect Ratio Also see the interactive tutorial:
An interactive demo shows you the effect of an incorrect pixel aspect ratio on an image.

27. Distortion Pixel Apect Ratios Distortion
video frame's = display system's
none
video frame's < display system's
stretched horizontally
video frame's > display system's
stretched vertically

28. Counting Time in Digital Video
Timecode: to number frames
SMPTE (Society of Motion Pictures and Television Engineers) video timecode
number frames in hours, minutes, seconds, and frames
drop-frame timecode
non-drop-frame timecode

29. Drop-frame Timecode
Example: 00;02;51;20 Video time is 0 hours, 2 minutes, 51 seconds, and 20 frames
Use semi-colons (not colons)
Perferable for the NTSC system

30. Drop-frame Timecode
Does NOT mean dropping or removing frames from the video
NTSC video is fps, not exactly 30 fps
Drop-frame timecode renumbers frames to make the timecode more accurately represent the video time based on fps

31. Non-Drop-frame Timecode
Example: 00:02:51:20 Video time is 0 hours, 2 minutes, 51 seconds, and 20 frames
Use colons

32. Review Questions Note to instructor:
Depending on your preference, you may want to go over the review questions at the end of this lecture as an instant review or at the beginning of next lecture to refresh students' memory of this lecture.

33. Review Question
True/False: There is no sampling and quantization involved in capturing motion in digital video.
False

34. Review Question The frame size of a video refers to the video’s ___.
aspect ratio
pixel aspect ratio
resolution
ppi C

35. Review Question
True/False: The pixel per inch (ppi) is an important attribute for video resolution and should be set correctly when working with digital video in video-editing programs.
False

36. Review Question Pixel aspect ratio means ___.
the ratio of a frame’s width (in pixels) to the height (in pixels)
the ratio of a frame’s height (in pixels) to the width (in pixels)
the ratio of a pixel’s width to its height
the ratio of a pixel’s height to its width C

37. Review Question
The pixel aspect ratio of a wide-screen format standard definition video is ___.
4:3
16:9
1.0
0.9
1.2 E

38. Review Question
The pixel aspect ratio of a standard format standard definition video is ___.
4:3
16:9
1.0
0.9
1.2 D

39. Review Question
The frame aspect ratio of a wide-screen format standard definition video is ___.
4:3
16:9
1.0
0.9
1.2 B

40. Review Question
The frame aspect ratio of a standard format standard definition video is ___.
4:3
16:9
1.0
0.9
1.2 A

41. Review Question
If a frame with pixel aspect ratio 1.2 is displayed on a device using a pixel aspect ratio of 1.0, the image will be ___.
stretched horizontally
stretched vertically
cropped at the left and right edges
cropped at the top and bottom
displayed correctly B

42. Review Question
If a frame with pixel aspect ratio of 1 is displayed on a device using a pixel aspect ratio of 1.2, the image will look like ___. B

43. Review Question
True/False: The timecode representing the 35th frame is either 00:00:00:35 or 00;00;00;35.
False; it should be 00:00:01:05 or 00;00;01;05

44. Review Question
True/False: The drop-frame timecode drops or discards frames to preserve the time accuracy of a video.
False; it renumbers frames, not discarding frames

45. Review Question
Which of the following is the drop-frame timecode format?
00:00:00:00
00;00;00;00
00,00,00,00 B

46. Review Question
Which timecode format is preferable for the NTSC system?
drop-frame
non-drop-frame B